Portable crane



Oct. 19; A1937. R. G. LE 'rouRNEAu PORTABLE CRANE Filed Aug? 31,` 1936 2 Sheets-Sheet 4l Oct. 19, 193'?1 R. G. LE TOURNEAU 2,096,186

' v PORTABLE CRANE Filed @ug 31, 1956 u 2' Sheets-Sheena INVENTOR R.G.L6T0ur1zea w ATTORNEY BY Q Patented ocr. 19, 1937 UNITED. STATESl PATENT oli-*FICE- R. G. Le Tourneau,

Inc., Stockton, Calif., a

I corporation of California Application August 31, 1936, Serial No. 98,654

4 Claims.

'Ihis invention relatesto portable cranes for .general utility service on highways, shop or construction yards, and similar areasand particularly represents improvements over the tractor 5 mounted crane shown in my co-pending applicaltionifor patent, Ser. No. 45,040, led October 15,

' z35, issued on April 27, 1937 as Patent No. 2,078,- 3.

In the previous construction, the crane was arranged so that only a portion of the weight of the tractor was available as a counter-.balance for the load carried by the crane, so that the long tongue on the crane base was necessary to provide leverage sufcient to utilize this fragmentary portion of the tractor weight to the. best advantage. This made the crane as a whole so long that it could not be eiiiciently employed in relatively conned quarters.4 The previous crane was also arranged so that it was behind the tractor, making,

it necessary for the operatorof the `.latter (and who also controls the crane hoist and boom lines) to twist about in his seat on the tractor to see what he was doing.

The principal objects of the present' invention are to avoid the above objectionable features by varranging the crane so that it is ahead of and pushed by the tractor while at the same time enabling the crane to be easily steered or turned with the tractor asa unit; and by mounting the crane on the tractor so that the entire weight of the latter serves as a load counter-balance, thereby making it possible to shorten the base of the crane considerably and provide a correspondingly compact unit.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be4 exceedingly effective for the purpose for which it is designed. l

These objects I accomplish by means of such 40 structure and relative arrangement of parts as will fully appear by a perusal of the following snecication and claims. Y In the drawings similar characters of reference indicate corresponding parts in the several views:

Figure 1 is a side elevation of -Imy' improved crane as mounted on a tractor.

Figure 2 is a top plan yiew of 'the same, with the operating cables removed.

Referring now more particularly tothe charac-v I'ters-of reference on the drawings, the crane 'comprises a base :frame in the form of side beams I rigidly connected at their forward ends by a cross beam 2.l The beams I slope down to their -rear end and at said end are provided with bear- 4 ing boxes 3 to engage trunnions I. These trunincludes upwardly converging side arms II havi nions are mounted on and project laterally from saddles or brackets 5 secured on the side frames ,G of the track units ofv a tractor I in such a position on the same as to be substantially-central of the longitudinal distribution ofl weight of the 5 tractor.

Bosses 8project rearwardly from the cross beam 2y adjacent-its ends and support the kingpins of' swivel forwardly angled forks 9 in which caster wheels I0 are mounted. The base is thus capable 10 of swivel movement relative to the tractor in a vertical plane but is rigid with the tractor in a horizontal plane, so that as the tractor is turned to one side or the other, the crane base will turn likewise. Wheels swing also, sothat no interference'with )the desired ease of steering ofthe tractor is had.

The crane boom is substantially of the same form as shown in said co-pending application and ing a forgvard overhang I2 at their forward upper 20 end and from which the load engaging hook I3 or the like is supported by a conventional hoist cable arrangement I4. The cable I4 initially 'extendsover a guide pulley I5 from one drum of a 25 suitable double drum power hoist unit H mounted at the back of the tractor as is now common practice. The boom control cable I6 extends from the other drum of the hoist, to and between a sheave block. I1 mounted asa unit with the pulley I 5 30 and a sheave block I8 mounted on-the boom at v the top.

The block I 1 is mounted above the tractor substantially midway of the length and centrally of the width thereof onan auxiliary arch frame I9 35 which straddles the tractor and is rigid with the rear ends of the beams I, being braced from the cross beam 2' by a central brace bar 2li extending from said auxiliary frame under the block I'I and over the 'front of the tractor to the 40 cross beam.A The auxiliary frame is suiiiciently high so that the operator `of the tractor has unobstructed view ahead from under the s'ame.

The boom arms Il are pivotedat their lower ends on ears 2l upstanding from the cross beam 45 2 adj acentits ends and substantially in a common vertical plane with the axis of the wheels l0 when the latter are disposed in normally trailing relation, In this manner the load is carried directly over the wheel and also is counter-balanced by 50 the entireeweight of the tractor. Relatively largeA loads even with a considerable forward angling lof the boom may thus be handled Without any tendency to tip the tractor;

in tbe previous structure the boom is adapted As the tractorA thus turns the caster 15 to be raised to a. vertical position so that the load may be handled very close to the front end of the base. To prevent backward tipping of the boom from such position, I provide transversely spaced pads`22 adapted to rest on the auxiliary' cross beam 23 of the base when the boom is it is' necessary to do to eiectthis removal is to disconnect the bearing boxes 3 from the trunnions 4 and back the tractor away from the crane. The trunnion supporting brackets remain permanently on the tractor since they do not of course interfere with any of the normal operations thereof, and are the only parts of the structure which are permanently attached to the tractor.

From the foregoing' description it will'be readily seen'that I have produced such a device as substantially fullls the objects of the invention as setforth herein. i

While this specicationvsets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as dened by the appended claims. f

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. A portable crane comprising a base having side beams adapted to extend on opposite l.sides of a tractor from in front thereof, means to swivelly mount the rear end of the beams on the tractor, for `relative movement in a vertical plane, transversely spaced swivel caster wheels supporting the base ahead of the tractor and having the axis of the swivel horizontally oilset from the axis of the wheels, and a boom mounted on `and upstanding from the base ahead of the tractor.

2. A'portable cra'ne attachment for a tractor comprising a base frame which. includes side beams spaced to` straddle the tractor and a cross beam rigidly connecting the side beams at their outer ends, means to removably mount the side beams at their opposite endson the side frames of the tractor intermediate the ends of said side frames for swivel movement in a yertical plane, a sheave-supporting auxiliary frame rigid with and upstanding from the side beams adjacent said-opposite ends thereof and adapted to extend above and across the tractor, a boom mounted on the base frame adjacent ithe outer end thereof, and wheels supporting the base frame at said outer end thereof.

3. A structure as in claim `2, in which the side beam mounting means comprises brackets adapted to be secured on the side frames of the tractor and .trunnions on the brackets turnably engaging the side beams.

4. A structure asin claim 2, with a central diagonal brace `bar extending between and rigid with the cross beam and the auxiliary frame' at the top thereof.

RQBERT G. LE TOURNEAU. 

